Currently, the mobile terminal has been used more and more widely, and the function of the terminal has been very strong and is full of rich entertainment, people can listen music, watch television, access Internet and so on. In the process of using a mobile terminal, due to the limitation of battery capacity, people can find that the battery power is soon used up, and it often needs to charge the battery. The appearance of the wireless charging technology in which the electromagnetic induction is the representative gives consumers the convenience. A mobile phone can be easily charged through a wireless charging device, so that the consumers get rid of the shackles of cable.
There are many principles for realizing wireless charging, such as electromagnetic induction, resonance, RF transmission and so on. Due to advantages of the electromagnetic induction technology in efficiency, cost and safety, it is currently used widely in the consumer electronics field. Existing products are basically using the electromagnetic induction technology-based wireless charging technology. In order to promote the rapid development of electromagnetic induction wireless charging technology, two international organizations: the WPC (Wireless Power Consortium) and the PMA (Power Matters Alliance) have been established.
The Wireless Power Consortium is referred to as WPC and was founded in 2008, and it is the first organization promoting the wireless charging technology standardization in the industry. The WPC takes safety and charging efficiency as the starting point, uses the near-field electromagnetic induction technology as the international standard of the low power portable electronic device charging, and its label is defined as Qi. The electromagnetic induction technology is with centuries of history, because there is no contact point, it has high security and reliability in harsh environments, and in the technical specifications, its power distance is less than a centimeter, and the transmitting end can focally transmit the power to the receiving end.
The PMA (Power Matters Alliance) is launched by the Duracell Powermat company and is an electromagnetic induction based wireless charging standard. In 2012, industry giants such as AT&T, google, Starbucks etc. have joined in the PMA organization and are dedicated to promoting PMA standard-based wireless charging technology that currently has a lot of applications in the North American market.
Both the WPC and the PMA are wireless charging standards based on the electromagnetic induction technology, but they are different in technical details such as communication protocol, transmission frequency and so on. The WPC has been widely used in Asia and Europe; the PMA is conducting large-scale promotion in North America.